The invention relates to a belt retractor for a vehicle seat belt.
A belt retractor usually comprises a frame made of metal in which a belt reel is supported. The seat belt can be wound onto the belt reel. An interlock mechanism enables the belt reel to be locked as a function of predetermined parameters so that the seat belt can be unwound from the belt retractor either not at all or only against a very high retaining force so as to retain the vehicle occupant.
The belt reel usually consists of zinc die casting and includes a slit through which the belt webbing extends. For fastening the seat belt on the belt reel usually a pin is used which is inserted in a loop of the belt webbing and has a diameter larger than the thickness of the slit.
From patent literature it is moreover known to manufacture belt reels and/or the frame and the housing of the belt retractor of plastic material. This is intended, on the one hand, to reduce weight and, on the other hand, to reduce costs. Belt retractors of this type are known, for example, from EP 1 637 413 B1 and DE 40 23 662 A1. Casings and reels made of plastic material have not been practically used in automotive vehicles so far, however. Among other things, this is due to the fact that the safety requirements of the car manufacturers and legal load requirements, especially breaking loads, are so high that while maintaining the mounting volume of conventional belt retractors they have not easily been met as yet by casings and reels made of plastic material.